The json data has the form "message", "code", "action". If the form contains errors a code of 400 is replied together with a reasonable message. If zettel was able to produce rdf from the form it sends a code of 200 and the actual data in the message field.

To edit an existing resource you must send your data to the zettelform this can be done by posting form-data to the /forms route. You can also post rdf-xml data. Zettel will try to fill the form with your rdf data. You can achieve this by sending a message to the zettel iframe. Zettel listens to javascript events. Please use the following pattern: